Typically, from the standpoint of reducing maintenance, totally-enclosed rotary electric machines are often used as rotary electric machines for railway vehicles. A totally-enclosed rotary electric machine is principally composed of a tubular frame, in which a rotor is arranged on its inner peripheral side, and housings, which are arranged facing each other at both ends of the frame and which rotatably support the rotor shaft. Bearings are provided in the central portion of the housings and a cylindrical stator core, which accommodates therein stator coils, is attached to the inner peripheral portion of the frame, and a uniform space is formed between the inner peripheral surface of the stator core and the outer peripheral surface of the rotor.
With a totally-enclosed rotary electric machine configured as above, although a cleaning operation of the rotor and the like is not necessary, periodic maintenance of the bearings is necessary. When the maintenance is performed, it is typical to first extract the rotor from the frame and thereafter detach the bearings.
As a method to eliminate such an operation, the traction motor illustrated in Patent Literature 1 described below is provided with rotor supporting devices, which are for supporting the rotor, and support receiving units, which receive the rotor supporting devices. The rotor is fixed by pressing the rotor supporting devices against the support receiving units by a plurality of bolts inserted from a bearing bracket side and thereafter the housings, which fix the bearings, are disassembled.